This invention relates to a medical and surgical laser probe, and more particularly to a medical and surgical laser probe having, at a forward end thereof, a contact member made of a laser transmitting material so as to allow the probe to be used in contact with the tissue which is to be subjected to laser irradiation treatment.
There has already been developed and practically used a non-contact type laser irradiation probe made of an optical fiber for carrying out incision and coagulation of the tissue for a living organ through irradiation of laser beam emitted from the optical fiber. This type of laser probe makes incision or coagulation by irradiating laser beam such as Nd:YAG laser, Argon laser, etc. from the forward end of a laser beam guide of an optical fiber such as an elongated quartz core which is optically connected to a laser source.
Such a non-contact type laser irradiation probe is used in such a manner that it is kept a distance from the tissue so as not to contact the tissue for preventing possible burning of the laser emitting end of the optical fiber. This type of laser probe has no fatal problem and therefore desired effect can be obtained if the laser output is kept constant and the distance from the tissue is kept constant during the laser irradiation. In fact, however, it is quite difficult to keep the distance constant from the tissue because the living tissue moves by itself and it is also difficult for the operator to keep the distance constant by a free hand. Therefore, the effect of laser irradiation onto the tissue cannot be constant or uniform and a serious result is possibly caused onto the patient. This problem is most noticeable when the laser probe is used for laser irradiation treatment through endoscope.
The conventional laser probe has another problem that the divergency angle of laser beam which is emitted from the tip end of the optical fiber into air is as small as 7.degree. to 10.degree. and therefore the irradiation must be repeated to cover the entire area to be irradiated by laser beam and a considerable time is required to complete the irradiation. The probe has a further problem that since the laser is once emitted into air and onto the tissue, 30 to 40% of the emitted laser beam, in general, is backscattered from the surface of the tissue and a serious energy loss is caused.
With respect to protection of the laser emitting end of the optical fiber, i.e., cooling of the emitting end of the fiber and prevention of blood or mucus from entering the end of the fiber in the conventional laser probe, a gas is fed through a space between a sheath tube covering optical fiber and an outer tube covering the sheath tube and discharged outside of the probe to effect cooling of the laser emitting end of the fiber and expelling of blood and mucus. This also involves such a serious problem that a considerable amount of gas is needed to acquire a sufficient cooling effect because a gas generally has rather low cooling ability. For example, when the conventional laser probe of this type is used for irradiation onto an inner wall of stomach, the stomach is filled with a gas and swollen by the gas. This not only gives the patient unpleasantness but sometimes causes perforation in the stomach wall because laser is irradiated on the swollen and thinned stomach wall.
The typical structure of the conventional laser probe suited for hemostasis will now be described referring to FIGS. 9 and 10.
100 designates an optical fiber made for example of quartz covered by sheath 102. The fiber 100 is optically connected to a laser source. An outer tube 106 is coaxially provided around the sheath tube 102 keeping a gap 104 therefrom. An annular tip member 108 is disposed at the forward end of the tube 102 so that the laser emitting end of the optical fiber 100 may not directly contact the tissue. The outer tube 106 is fitted around a stepped portion of the tip member 108 so that the assembly has a smooth or flush surface. The stepped portion of the tip member 108 has two slits 110.
In use of this probe, laser beam irradiation is carried out keeping the probe distanced from the tissue and feeding a gas G through the gap 104 between the sheath tube 102 and the outer tube 106. The gas is guided into the tip member 108 through the slits 110 and discharged from the opening of the forward end of the tip member 108.
This conventional laser probe, however, cannot enlarge the divergency angle determined by the characteristics of the optical fiber 100 itself. Although the tip member 108 is provided and a gas is jetted to prevent blood etc. from entering the laser emitting end of the optical fiber 100 for protection of the probe, this cannot be prevented completely and the treatment is interrupted and serious result is caused when blood or mucus from the tissue enter the emitting end.
It is first consideration of the present invention to provide a medial and surgical laser probe capable of effecting contact irradiation and having improved operating efficiency.
It is another consideration of the present invention to provide a medical and surgical laser probe which is capable of protecting the laser emitting end of the optical fiber by preventing possible burning of the emitting end of the fiber.
It is further consideration of the present invention to provide a medical and surgical probe which is capable of eliminating energy loss due to backscattering of laser beam and capable of effecting irradiation by a reduced power.
It is further consideration of the present invention to provide a medical and surgical laser probe which is capable of enlarging a divergency angle of laser irradiation so as to increase the irradiation area and reducing the time required for irradiation of the entire area to be irradiated.